The ups and downs of clas­sic lift and drop glass

Classic Car Weekly (UK) - - Living With Classics - fuzz town­shend CCW’s master Me­chanic

‘With all wind-down win­dow types, lu­bri­ca­tion of the op­er­at­ing gear and chan­nels is es­sen­tial and oftover­looked’

For the first quar­ter of a cen­tury of the mo­tor car, if any side pro­tec­tion from the el­e­ments was of­fered at all, it was of­ten in the form of the slid­ing win­dow ar­range­ment. This al­lowed beefy arms to not only steer heavy steeds in con­fined spa­ces, but to make fran­tic hand sig­nals too, and was a huge leap for­ward from the days of cock­pits that were to­tally open to the el­e­ments.

How­ever, slid­ing win­dows re­quired fid­dly catches to keep them from slid­ing open on brak­ing and, of­ten, an­noy­ing rat­tles grad­u­ally worked their way in to the con­scious aware­ness of the car’s oc­cu­pants, not to men­tion whistling draughts whisk­ing about whiskers.

Fric­tion drop win­dows ap­peared for a while, of the type that may still be seen in use on the car­riages of In­ter­City 125 rolling stock, but a more pos­i­tive drop-type so­lu­tion was needed, and this came in the form of the wind-up/down win­dow.

These ar­rived in smaller cars from the 1930s on­wards and were op­er­ated via a num­ber of mech­a­nisms. Per­haps the cheap­est and most ubiq­ui­tous of the op­er­at­ing gear was the pin­ion-and-quad­rant. Ini­tially rea­son­ably high qual­ity com­po­nents were used, in­clud­ing bronze pin­ions and cast quad­rants, but the need to re­duce cost was paramount, for com­mer­cially com­pet­i­tive rea­sons and so pressed steel and drop-forged com­po­nents quickly be­came the norm.

Achiev­ing smooth oper­a­tion wasn’t al­ways easy and so rack-and-pin­ion was a pos­i­tive, al­beit more expensive so­lu­tion to the prob­lem. The drop glass was at­tached to the rack at ei­ther side, ef­fec­tively each end of the curled around flex­i­ble rack, en­sur­ing even lift­ing and low­er­ing, with slightly less strain on the com­po­nents than the quad­rant type. In an ef­fort to keep wind-down win­dows from low­er­ing un­evenly, some man­u­fac­tur­ers opted for steel ca­ble oper­a­tion. This pro­vided a rel­a­tively light­weight and sim­ple form of oper­a­tion, but it was fid­dly to set up, es­pe­cially when re­in­stalling the mech­a­nism.

The three above-men­tioned meth­ods of oper­a­tion all lent them­selves to mo­torised oper­a­tion, when this be­came de­sir­able, first in lux­u­ri­ous, high-end mo­tor cars and now in vir­tu­ally ev­ery ve­hi­cle in man­u­fac­ture.

Of these com­mon types, the most dif­fi­cult to ser­vice with re­gard to clas­sic cars was the cheaper, pressed steel item. Of­ten, the rel­a­tively soft steel teeth on ei­ther the pin­ion or quad­rant wore away to the point that the winder slipped when op­er­ated.

Some of the more com­mon ap­pli­ca­tions re­main in pro­duc­tion and so some­times a spot of can­ni­bal­i­sa­tion of new units to re­pair un­avail­able older types is pos­si­ble.

With all wind-down win­dow types, lu­bri­ca­tion of the op­er­at­ing gear and chan­nels is es­sen­tial and oft-over­looked, but cer­tainly helps to keep the sys­tem work­ing as de­signed.

Drop glass rub­ber seals also need to be in good or­der to pre­vent wa­ter and dirt ingress, both of which cause early fail­ure of the mech­a­nism.

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